Magnetic dummy fuse plug



Augl7, 1937. n.. J. MONTGOMERY ET Al. 2,090,302

MAGNETIC DUMMY FUSE PLUG Filed May 4, 1934 3 Sheets-Sheet l Aug. 17,1937.

L. J. MONTGOMERY ET AL.

MAGNETIC DUMMY FUSE PLUG s sheets-sheet 2 Filed May 4, 1934 INVENTOR LJ. Momyomeg' 6 #3056/7 ATTORNEY Aug. 17, 1937'. J. MONTGOMERY ET Al.

MAGNETIC DUMMY FUSE PLUG Filed May 4,- 1934 3 S'xeelZs--Sheei'l 3INVENTOR L! -MongawelygfC/c/r ATTORNEY Patented Aug. 17, 1937 MAGNETICDUMIHY` FUSE PLUG Lawrence J. Montgomery,

Douglaston, and

Charles H. Bosch, Brooklyn, Y.

Application May 4, 1934, Serial No. 723,892

14 Claims. (Cl. 173-356) This invention relates'to dummy fuse plugsintended to be installed in place of screw plug fuses in common use forconnecting the mains of electrical supply companies to the house linesof individual consumers. The dummy plugs are substituted when the supplyof electricity is to be discontinued for non-payment of bills or otherreasons. They'diifer from fuse plugs in that they do not complete thecircuit through the socket and are designed to be non-removable exceptby those persons equipped with suitable tools or devices.

According to the present invention a dummy fuse plug is provided whichdepends for its manip- 15. ulation on magnetic means.

corporates within 'a body of insulating material an armature or othermagnetic-responsive means, and it requires the actuation of such meansbefore the plug can be manipulated for insertion or n removal; the bodycan be formed from porcelain,

molded phenolic resin composition or other suitable insulating material.The armature or other magnetic-responsive means is concealed within theplug body to render it inaccessible and to require the application of amagnetic means for its operation; such magnetic means can be appliedexternally of the plug to operate the responsive means, or the magneticImeans can be incorporated in the plug structure. The responsive meanscan take various forms such 'as a movable pin, a bar, or a plate and itcan be either of the attraction or repulsion type. Preferably apositively acting biasing means such as a spring is included to opposethe action of the magnetic means for insuring proper positioning of themagnetic-responsive means withinthe plug and for maintaining theresponsive means in that position when not acted upon by a magneticmeans.

In order that the invention may be clearly understood and its scope madeevident, several specic embodiments are illustrated in the accompanyingdrawings and hereinafter described. The invention, however, isnotlimited to thesespeciiic embodiments but is to be given aninterpretation commensurate with the appended claims.

Referring to the drawings- Fig. 1 is a. vertical cross section of anassembly of a fuse socket and a one piece dummy plug constituting oneembodiment of the invention;

the gure also illustrates a fragmentary portion of an electromagnetplaced in position'relative to the plug but not energized.

Fig. 2 is a top view of a two-part plug illustrating a. secondembodiment of the invention;

Fig. 3 is a vertical cross section of line 3-3 of To this end it in-Fig. 2; Fig. 4 is a cross section similar to Fig. 3 but illustrating inaddition a fragmentary portion of an electro-magnet and themagnetic-responsive means in the position occupied when the magnet isenergized; Fig. 5 is a cross section sim- 5 ilar to Fig. 3 but with thethe cover part of the plug rotated at degrees with reference to the basepart; and Fig. 6 is a fragmentary vertical cross section similar to Fig.3 but illustrating a modified form of magnetic-responsive means. 10

Fig. 7 is a side elevation of a two-part plug illustrating a thirdembodiment of the-invention; Fig. 8 is a horizontal cross section on theline 8-8 of Fig. '7; and Fig. 9 is a vertical cross section on the line9-9 of Fig. 8. l5

Fig, 10-is a vertical cross section of a fourth embodiment of theinvention as applied to a twopart plug; Fig. l1 is a view similar toFig. 10 but including a -fragmentary portion of a magnetic means appliedto the plug and illustrating the 20 magnetic-responsive means in theposition occupied when the magnet is energized; Fig. 12 is a horizontalcross section on the line |2-l2 of Fig.

10 but with the magnetic-responsive means omitted; and Fig. 13 is a. topplan view of the 25 magnetic-responsive means included in the embodimentshown in Fig. 10.

Fig. 14 is a vertical cross section of a iifth embodiment of theinvention illustrating in vertiv cal cross section a two-part plughaving incorpo- 30 rated therein a magnetic means in addition to amagnetic-resp-onsive means; Fig. 15 is a view similar to Fig. 14 butillustrating in addition the application of energizing means for themagnet and the armature in a raised position which it 35 occupies whenthe magnet is energized; Fig. 16 is a top plan View of the armatureincorporated in the embodiment of Fig. 14; and Fig. 17 is a top planview of the base part of the plug illustrated in Fig. 14. 40

Fig. 18 is a cross section of a casing illustrating enclosed batteriesin diagrammatic form and having terminals for energizing anelectromagnet.

Fig. 19 illustrates in vertical cross section a 45 sixth embodiment ofthe invention as applied to a two-part plug and embodying a repulsiontype of magnetic-responsive means; and Fig. 20 is a view similar to Fig.19 but illustrating in addition a fragmentary portion of a magneticmeans 50 and showing the responsive means in repelled position. Fig. 21is an elevation of a permanent magnet which can be used with the.various embodiments illustrated; Fig. 22 is a vertical cross section of55 an electromagnet and shown in conjunction with the cover part portionof the embodiment illustrated in Fig. 3; and Fig. 23 is a fragmentarytop view of the cover part illustrated in Fig. 22. I Referring to theassembly shown in Fig. 1 a cut-out base I supports a fuse socket 2 thatis connected to a terminal 3 by the fitting 5 and to a terminal 4 by thefittings 6 and 1. The dummy fuse plug shown as mounted in the socket l 2consists of a one-piece body 8 having screw threads 8 formed thereon forengagement with the socket. The body 8 has an internal cavity l0 inwhich is hingedly mounted a lever arm II biased to one side by a springl2. 'Ihe arm 16 carries a sharpened end I3 for cutting into the thinshell of the fuse socket; the end I3 is driven into the shell by thespring I2 and prevents unscrewing oi the plug from the socket. The armcarries an armature l so formed and l0 located as to be attracted by anelectro-magnet I5 when the magnet is brought into external contact withthe plug and is energized by an electric current. Attraction of thearmature by the magnet withdraws the sharpened end I3 from the shell 2,thereby leaving the plug free for unscrewing from the socket. Ininstalling the plug the electro-magnet is applied and energized so as tokeep the end I3 from contact with the shell; after the plug is screwedin place into the socket the electro-magnet is removed and the spring i2thereupon presses the end I3 into the shell.

In the embodiment illustrated by Figs. 2 to 5 inclusive a two-part plugis illustrated consisting of the base I 6 and the cover I'I.V The basei6 is screw threaded to engage a fuse socket and the cover i1 isswivelled on the base by means of a rivet i8 molded into the cover andfree to turn in the base I6. The cover I1 has a cavity IB whichregisters at one position with a similar cavity 20 in the base; thesecavities as shown are cylindrical and have their axes parallel to oneside of the rivet I8. VWhen the plug parts are assembled these cavitiesare inaccessible from the exterior of the plug. Within the cover cavityI9 there Yis a spring 2l adjacent its closed end and a cylindricalpellet 22 pressed by the spring; the pellet is shorter than the cavityand is loose therein. The base cavity 20 is substantially filled by acylindrical pellet 23 fitting loosely in the cavity so that it can slidefreely therein. When the cavities I 9 and 20 are in register as shown inFig. 5 the pellet 22 is pressed against p the pellet 23 by the spring2l, but since the pellet 23 lls the cavity 20 the pellet 22 does notextend below the contact surface of the base and cover parts. The covercan therefore be freely rotated upon the base and into a position suchas shown in Fig. 5. When the cavities are again gofbrough't intoregister and an electro-magnet ap plied (shown in'Fig. 4 as made up of acore 25 and a winding 24) and the magnet is energized, the pellets arepulled up against the action of the spring 2i by the magnet thus drawingthe g5 pellet 23 into the cavity 20. The base and cover are then lockedagainst relative movement by the pellet 23 extending into both cavitiesso that the plug may be screwed into a fuse socket or removed -from afuse socket by turning the cover. 70 Upon deenergizing the magnet orremoving the magnet from the plug the spring 2l depresses the. pellet 23into its cavity 20 through the pellet 22, thereby unlocking the coverfrom the base so l that the base can again be freely rotated. 75 Toinsure :freedom of rotation. when there is no magnetic action appliedmodified forms of pellets as shown in Figure 6 can be substituted.According to the disclosure of this figure a reduced cavity 20 isprovided in which fits a pellet 23. I'he pellet 22 carried in the cavityi9 is accordingly too large to enter the cavity Maand therefore ridesupon the surface of the base when the cover is rotated.

In the embodiment of Figs. 7, 8, and 9 a. plate armature is disclosed. Atwo-part plug consists of the cover I'IEL and base I6 swivelled togetherby a rivet I3. The cover is made with a cavity y2li 'that is cylindricalin shape with the exception of two cast-in projections 21. The base I5acarries two cylindrical pins 28 which extend into the cavity 26. Anarmature plate 29 rests on shoulders 3| formed on the pins 28, andsprings 30 on the pins force the plate against the shoulders 3i;

notches 32 are formed in the plate to register with.

the projections 21.

When an energized electro-magnet is applied to the cover Il it attractsthe armature plate 29 against the bias of the springs 30. 1f the coverI1 is then rotated with relation to the base until the notches 32register with. the projections 21, the plate is lifted by the magnetagainst the action of the springs rto cause the projections to enter thenotches. lSince the pins 28 prevent rotation of the plate 29 withrespect to the base llim and the projections 21 'iorm a part of thecover Ila, the base'and cover are thereby locked against the relativerotation; the plug can thereupon be screwed into or out of a fuse socketby turning the cover .119'. Upon removal of the magnet the springs 30press the plate 29 against the shoulders 3i thereby releasing theprojections 21 so that the cover is free to rotate on the base.

Toassist in rotating the plug when the base and cover are lockedtogether through the energizing action of a magnet,vcavities 33 can beprovided in the cover to cooperate with pins `313 extending from amagnet. Such a construction of the magnet is shown in Fig. 11. By thismeans rotation of the magnet causes rotation of the cover and thereforeof the base through locking engagement of the armature plate 29.

In the embodiment of the plug shown in Figs. 10 to 13 the plate of Fig.9 is substituted by a movable armature cup 38. To accommodate the cupthe cover I1b is provided with a similarly shaped cavity, and the baseIISb is provided with a cavityinto which the cup can be depressed. Thecup is sliclably mounted on the rivet I8b securing the cover I Ib to thebase IB". and a spring 31 carried by the rivet serves to bias or forcethe cup into the base cavity. In order to obtain a, locking engagementby means of the cup, lugs 40 are formed on the cup 38; these lugs ridein notches 4I provided in the base I6b and also engage notches 39 formedin the cover 11b when the cup 38 is raised so as to lift the lugs abovethe surface of the base and when the notches 39 and 4I are in register.The cup is raised by applying a magnet as Shown in Fig. 1l to the coverand energizing the magnet; upon removal of the magnet the springdepresses the cup so as to release the lugs 4D from engagement with thenotches 39 and thereby promote free rotation of the cover on the base.

In the embodiment of Figs. 14 to 17 inclusive an electro-magnet isincorporated as part of a two-part plug consisting ci the base I6c andcover Il? held together by the rivetl. Within a cavity in the base thereis provided an armature J3 consisting of a tubular extension 44 and aange 45; the tubular portion slides on the rivet ||lc and is biased intoa depressed position by a spring 31c carried by the rivet. Anelectro-magnet 46 consisting of a coil of insulated wire wound on aninsulating form 48 is secured in a cavity in the cover its ends arebrought out i'nto holes 49 extending to the exterior of the cover andprovided with terminals 41. The extension 44 of the amature rides withinthe electro-magnet 46. The iiange portion 45`of the armature 43 isformed with notches 52 to engage projections y5| extending from the baseand thereby prevent turning of the armature with respect to the base.There are also projections 53 formed on the cover to be engaged by thenotches 52 when brought into register. When the electro-magnet is to beenergized a cap 55 carrying terminals 56 of a supply? line 54 is placedin position so that the terminals contact the coil terminals 41. Whenthe current is turned on the electromagnet is thereby energized to liftthe armature 43, and when the projections 53 are in register with thenotches 52 of the armature the cover becomes locked to the base; uponcutting olf the current the spring 31c depressess the armature andreleases the cover.

In Fig. 18 there is disclosed three dry batteries 51 within a casing 58having terminals 59 to engage the terminals 41. 'Ihis means of providingthe electro-magnet 46 with current can be substituted for the cap 55when the magnet 46 is' designed for operation on low voltage directcurrent.

When magnetism set up by an alternating current coil links with a closedconducting circuit, a current is caused to flow in that circuit byelectromagnetic induction; the conducting circuit is thereupon repelledmechanically by the reaction of the magnetic forces between the coil andthe closed circuit. I'his principle is applied in the embodiment shownin Figs. 19 and 20 in which a base I6d is swivelly secured to a cover|1d by a rivet 6|; the rivet 6| has formed with it a core `of magneticmaterial 62 which may be in one piece or more as desired. The core 62which is iixed to the cover |1d extends into a cavity 63 in the base|6d. A'ring 64 of conducting metal preferably copper, slides freely onthe core 62 and is biased into the cavity formed in the cover |11d by aspring 31d; the latter is seated in an annular recess 65 in the base.The conducting ring 64 is notched at diametrically opposite pointstocooperate with projections formed in the base and also in the cover asexplained in the description of the previous embodiment. When anenergized coil 66 is placed about the core 62 as illustrated in Fig. 20,the current set up in the conducting ring 64 results in its magneticrepulsion by the coil 66 awayfrom the cover |1d and toward the base I6dto lock the cover and base together; upon removal of the current thespring 31d returns the ring to unlock the base and cover.

As an external magnetic means for causing operation of themagnetic-responsive means,a permanent magnet can be used as illustratedin Fig. 21. Such a magnet may be a straight bar magnet or shaped as ahorse-shoe or given any other suitable form. In general, however, it ismore convenient to apply an electro-magnet as shown in Fig. 22. Astherein disclosed a magnet is automatically energized when it is pressedinto operating relation with a plug and is deenergized when it isremoved. This is accomplished by providing a core25a that is hollow andhas a plunger 61 sliding through it; the core is enclosed by aenergizing the magnet.

coil 24a. The plunger is in contact with a spring member 69 through aninsulating end- 68 whereby it is forced outwardly from the core. Whenthe plunger is moved inwardly through engagement with the cover of aplug, a contact 10 carried by the piece 69 is pressed into engagementIwith another contact 1| thereby closing a circuit and Upon release ofthe plunger 61 the spring member 69 breaks the engagement of thecontacts 10 and 1| and thereby deenergizes the magnet. This constructionprevents over-heating of the magnet, since connection is establishedonly when the magnet is in use for this reason a smaller size of magnetis possible than would otherwise be practical. The cover-engaging end 66of the core can be made square in cross section to t a similarly shapedcavity 33 in the cover.

We claim:

1. A dummy plug for a threaded fuse socket comprising in combination athreaded base for engagement with the fuse socket, a cover swiv eled, onsaid base, cavities in said base and said cover with open ends in theadjacent faces there- 'of and positioned for bringing into register, a

loose pellet of magnetic material in the cavity of the base and having aconguration permitting entry into the cavity of the cover, springpressedmeans in the. cavity of the cover normally preventing entry ofl thepellet into the cavity of the cover when the cavities are in register,and means limiting the entry of the pellet to a partial removal from thecavity in the base when drawn by magnetic means into the cavity of thecover to thereby lock the members together, said spring-pressed meansforcing the pellet from the cavity in the cover upon discontinuance ofthe operation of the magnetic means to unlock the base and cover andpermit relative rotation.

2. A dummy plug according to claim 1 comprising as the spring-pressedmeans in the cavity of the cover a loose pellet and a spring between thepellet and the bottom of the cavity acting on the pellet to force itoutwardly.

3. A dummy plug according to claim 1 comprising as the spring-pressedmeans in the cavity of the coverva loose pellet of a size too large toenter the cavity in the base and a spring between the pellet and thebottom of the cavity acting on the pellet to force it outwardly.

4. A dummy plug according to claim 1 wherein the cavities arecylindrical in shape'with their axes parallel to and adjacent to thecommon axis of the swiveled members, and wherein the pellet iscylindrical.

5. A dummy plug for a threaded fuse socket comprising in combination athreaded base for engagement with the fuse socket, a cover swiveled onsaid base, cavities in said base and said cover with open ends in theadjacent faces thereof and positioned for bringing into register, aloose pellet of magnetic material in the cavity of the base`and having aconfiguration permitting entry into the cavity of the cover,spring-pressed means in the cavity of the cover normally preventingentry of the pellet into the cavity of the cover when the cavities arein register, electro- "magnetic means associated with the plug and inpellet from the cavity in the cover upon discontinuance of the operationof the magnetic means to unlock the base and the cover and permitrelative rotation.

6. A dummy plug according to claim 5 having the electromagnetic meansseparablev from the plug, andmeans on the cover for engagement by theelectromagnetic means whereby the plug can be rotated by theelectromagnetic means,

7. A dummy plug for a threaded fuse socket comprising in combination athreaded base for engagement with the fuse socket, a cover swiveled onsaid base, the body formed by the base and the cover having a cavitytherein, a magnetic material plate within the cavity and movable thereinfrom one position to another, means connected with said plate forsimultaneously engaging 'the base and the cover in one position of theplate to lock the base and the cover against relative rotation, springmeans 'within the cavity and engaging the plat-e -for biasing the plateto a position out of simultaneous engagement with the base and the covert0 thereby permit relative rotation, and electromagnetic meansassociated with the body and in cooperative relation to the plate fordrawing the latter into the position for locking the base and the coverwhen energized.

8. A dummy plug tor a threaded fuse socket comprising in combination athreaded base for engagement with the fuse socket, a cover swl'veled onsaid base, the body formed by the base and the cover having a cavitytherein, an armature within the cavity and movable from one position toanother, an electromagnet mounted in the body in cooperative relation tothe armature, means connected with said armature for simultaneouslyengaging the base and the cover in one positiony of the armature to lockthe base and cover against relative rotation, and spring means withinthe cavity and engaging the armature for biasing the armature to aposition out of simultaneous engagement with the base and the cover tothereby permit relative rotation, said electromagnet when energizedserving to draw the armature into the position of locking the base andthe cover. f l

9. A dummy plug for a threaded fuse socket comprising in combination athreaded base for engagement with the fuse socket, a cover swiveled onsaid base, the body formed by the base and the cover having a cavitytherein, a ring of electrically conducting material in said cavity andmovable from one position to another, means connected with said ring forsimultaneously engaging the base and the cover in one position o! thering to lock the base and cover against relative rotation, spring meanswithin the cavity and engaging the ring to bias the ring to a positionout of simultaneous engagement with the base and the cover to therebypermit relative rotation, and an alternating current primary coilassociated with said body and in cooperative relation to said ring tofset up when energized a secondary current in said ring by induction tothereby cause repulsion of the ring into the locking position.

10. A dummy plug for a threaded fuse socket comprising in combination athreaded base for engagement with the socket, a cover swiveled on saidbase, the body formed by the base and cover having a cavity therein, acore of magnetic material fixed in said cover and extending within thebody and in cooperative relation with the core to g set up whenenergized a secondary current in said ring by induction to thereby causerepulsion of the ring into the locking position.

11. .A dummy plug for a threaded fuse socket comprising in combination athreaded base for engagement with the socket, an exposed manipulativemember'of electrical insulating material swiveled on the base,magnetically responsive means movably supported within the body formedby the base and the member, and means for connecting said responsivemeans simultaneously with the base and the member to enable manipulationof thc plug in the socket when the responsive means is energized by amagnet.

l2. A dummy plug for a threaded fuse socket comprising in combination athreaded base for engagement with the socket, an exposed manipulativemember of electrical insulating material swiveled on the base,magnetically responsive means movably supported within the body formedby the base and the member, means for connecting said responsive meanssimultaneously with the base and the member to enable manipulation ofthe plug in the socket when the responsive means is energized by amagnet, and biasing means within the body and in association with saidresponsive means for positioning the responsive means out ofsimultaneous connection with the base and the member. y

13, A dummy plug for a threaded fuse socket comprising in combination athreaded base of electrical insulating material for engagement withV-the socket, an exposed manipulative member of electrical insulatingmaterial rotatably secured to the base, magnetically responsive meansmovably supported within the body formed by the base and the member, andmeans for connecting said responsive means simultaneously with the baseand the member to enable manipulation of the plug in the socket when theresponsive means is energized by a magnet.

14. A dummy plug for a threaded fuse socket comprising in combination athreaded base of electrical insulating material for engagement with thesocket, an exposed manipulative member of electrical insulating materialrotatably secured to the base, magnetically responsive means movablysupported within the body formed by the oase and the member, means forconnecting said responsive means simultaneously with the base and themember to enable manipulation of the plug in the socket when theresponsive means is energized by a magnet, and biasing means within thebody and in association with said responsive means for positioning theresponsive means out of simultaneous connection with the base and themember.

LAWRENCE J. MONTGOMERY. CHARLES H; BOSCH.

